Study maps 10,000 hectares for Philippine eagles in Leyte

MANILA, Philippines — More than 10,000 hectares of forests in Leyte have been identified as potential release sites for Philippine eagles, offering conservationists a science-based guide as they work to restore the critically endangered raptor to an island where it once thrived.

Published in the Philippine Journal of Science, the study identified around 10,320 hectares of suitable release areas within the Anonang-Lobi Mountain Range and Mt. Nacolod Key Biodiversity Areas. Of these, about 9,554 hectares were classified as the “most suitable” because they are located farther from human settlements and meet habitat and safety requirements for future releases.

The findings come as the Philippine Eagle Reintroduction Program continues efforts to establish a new wild population in Leyte through a partnership involving the Department of Environment and Natural Resources, the Philippine Eagle Foundation, local governments, universities, conservation organizations and communities.

READ: DENR, PEF, PNP unite to restore PH Eagle population in Leyte forests

For researchers, the study fills an important gap in the country’s conservation efforts. While earlier habitat modeling had shown that Leyte still contains forests capable of supporting Philippine eagles, there had been no detailed spatial analysis identifying where future birds could be released while minimizing risks from human activities and other threats.

Philippine Eagle Lakpue soars above Leyte’s forests after his reintroduction in 2025, a hopeful sight for the return of the species to its historic island home. (Photo courtesy of the Philippine Eagle Foundation)

Using geographic information systems, expert consultation and multicriteria decision-making, the researchers assessed ecological conditions alongside human-related factors to identify areas that could improve the chances of successful reintroduction.

Lead author Demi Julianna L. Gentiles and fellow researchers from the University of the Philippines Diliman’s Department of Geodetic Engineering worked with experts from the PEF to evaluate several variables, including forest habitat, terrain, roads, settlements, human footprint, possible power-line risks and access for conservation teams during release operations.

The resulting maps highlight forest landscapes connected to parts of Ormoc City, Baybay City, Kananga, Burauen, Silago, Mahaplag, Sogod and Javier, where future releases could eventually take place after further field validation.

A return to an old home

The Philippine eagle once formed part of Leyte’s native wildlife, but decades of deforestation, habitat degradation, hunting and other human-related pressures gradually reduced the island’s eagle population.

Researchers noted that by the time Super Typhoon Yolanda devastated Leyte in 2013, the remaining population may already have been “very small and vulnerable.” The destruction brought by the typhoon likely added further pressure to birds that were already struggling to survive.

The study also noted that eagle sightings on the island had long been rare. Following Yolanda, annual surveys conducted by the Philippine Eagle Foundation no longer detected the species, prompting efforts to reestablish a breeding population through reintroduction.

That effort formally began in 2024, when conservationists released the first two Philippine eagles in Leyte. Three more birds followed in 2025, marking the country’s first attempt to reintroduce rescued and rehabilitated Philippine eagles outside Mindanao.

GRAPHIC: Ed Lustan/INQUIRER.net

Together, the five birds represent the first of several planned release batches involving 16 eagles, with the long-term goal of establishing six breeding pairs within the Anonang-Lobi Mountain Range.

READ: Philippine eagle pair released in forests of Leyte

The new study is intended to strengthen those future releases.

“Successful reintroduction starts with good science,” said Dr. Jayson C. Ibañez, PEF director for operations and one of the study’s co-authors.

“This research helps us identify where future Philippine eagles can be safely acclimatized and soft-released into the wild. By identifying suitable hack sites, we can improve the chances that released birds will adapt to their new environment and eventually establish territories in Leyte’s forests,” Ibañez said.

The researchers stressed that selecting a release site involves far more than finding an intact forest.

The study explained that Philippine eagles require vast territories because they are large, top predators that need enough forest to hunt, breed and avoid competition with other pairs.

They also have a slow reproductive cycle, producing only one egg every two years and providing extended parental care.

GRAPHIC: Ed Lustan/INQUIRER.net

The remaining suitable forests in Mindanao are also believed to be largely occupied by existing breeding pairs, leaving limited room for the species’ population to expand naturally.

“This lack of available, unoccupied habitat necessitates the identification of viable reintroduction sites on other islands,” the study noted.

Leyte emerged as the first site for the country’s experimental reintroduction of rescued and rehabilitated Philippine eagles outside Mindanao.

“Leyte was particularly chosen since current genetic studies imply that there is no genetic divergence between Mindanao and Visayas eagle populations, suggesting that the individuals can be mixed,” the study said.

How researchers mapped the sites

The researchers used geographic information systems alongside expert input to identify areas in Leyte that could give reintroduced Philippine eagles the best chance of surviving in the wild.

Rather than looking at forest cover alone, they also assessed terrain, habitat quality, human activity, proximity to settlements, roads and potential power-line risks.

The study identified two categories of potential release sites. Areas classified as “suitable” are at least 150 meters away from human settlements, while “most suitable” areas are located more than 500 meters away, where human disturbance is expected to be lower.

Using those criteria, the researchers identified about 10,320 hectares of candidate release sites across the Anonang-Lobi Mountain Range and Mt. Nacolod. Of that total, 9,554 hectares were classified as the “most suitable” for future releases.

Many of the identified sites are within the Anonang-Lobi Mountain Range, a Key Biodiversity Area recognized for supporting threatened wildlife and one of the Philippine Eagle Foundation’s priority conservation landscapes.

RELATED STORY: PH eagle ‘Lakpue’ soars again in Leyte forests

GRAPHIC: Ed Lustan/INQUIRER.net

The study also identified Mt. Nacolod in Southern Leyte as another promising landscape. Its old-growth, secondary and mossy forests provide habitat for a wide range of wildlife, including documented Philippine eagle sightings, while also serving as important watershed areas for surrounding communities.

Researchers also mapped 13 potential helipad sites, particularly around the Anonang-Lobi Mountain Range, to support the transport and release of eagles into remote forests.

Several are near Mt. Aminduen, or Alto Peak, the highest mountain in Eastern Visayas, which the study identified as having favorable habitat characteristics for the species.

For Gentiles, a BS Geodetic Engineering student, the project demonstrated how mapping technologies can directly support wildlife conservation.

“This research showed us and my student co-authors how GIS, mapping, and spatial analysis can help solve real conservation challenges. It also taught us that conservation is a collaborative effort involving students, scientists, conservation practitioners, government agencies, and local communities working toward a common goal,” Gentiles said.

Potential release sites for Philippine Eagles identified in the Anonang-Lobi Mountain Range (a) and Mt. Nacolod (b). (Map from: “Identifying suitable release sites for Philippine eagles in Leyte for aiding reintroduction using GIS-based multi-criteria decision-making”)

Dr. Alexis Richard C. Claridades, corresponding author of the study and a faculty member at UP Diliman’s Department of Geodetic Engineering, said the findings show the value of using evidence to guide conservation planning.

“Conservation works best when it is guided by evidence. GIS and spatial analysis allow us to identify locations that offer the best opportunities for species recovery. These tools help conservation organizations and government agencies make informed decisions and direct resources to areas where they can have the greatest impact,” Claridades said.

Science guiding conservation

For PEF, the study is more than a map of potential release sites. It provides a scientific basis for decisions that could shape the future of one of the world’s rarest birds of prey.

Dennis I. Salvador, the foundation’s executive director, said the research highlights the growing role of universities and scientific institutions in conservation work.

“One of the most important developments in conservation today is the growing contribution of academia. Studies such as this provide the scientific foundation for conservation action. Through our network of academic partners and experts, the Philippine Eagle Foundation is able to support the DENR’s mandate of protecting biodiversity with sound science,” Salvador said.

He said restoring Philippine eagles to Leyte will require sustained cooperation among government agencies, researchers, local communities, conservation groups and the private sector.

“No single organization can save the Philippine Eagle alone. Conservation requires the combined efforts of government agencies, universities, local communities, conservation groups, and the private sector. This study is a good example of how partnerships can generate the knowledge needed to guide conservation action,” Salvador said.

The Anonang-Lobi Key Biodiversity Area in Leyte now shelters reintroduced Philippine Eagles, giving them space to soar once again in the island’s forests. (Photo courtesy of the Philippine Eagle Foundation)

The study itself reflects that collaboration. Researchers from UP Diliman worked with experts from the Philippine Eagle Foundation to develop the criteria used to identify suitable release areas, drawing on the foundation’s decades of experience in eagle conservation.

The findings have also drawn support from local governments whose forests were identified as potential release landscapes.

Javier Mayor Michael Dragon Javier welcomed the inclusion of his municipality among the areas that could support future eagle releases.

“We are delighted to learn that the forests of Javier were identified among the areas capable of supporting future Philippine Eagle releases. Even before the study was published, its findings inspired our municipality to express its willingness to host a future eagle release and commit local government resources to help make it happen,” Javier said.

He added that protecting habitat for the Philippine eagle also helps safeguard natural resources that communities rely on.

“Conserving forests for Philippine Eagles also means protecting our watersheds, preserving biodiversity, and maintaining carbon sinks that help address climate change. The people of Javier depend on healthy forests for water, livelihoods, and quality of life,” Javier said.

RELATED STORY: Wounded Philippine eagle rescued along Leyte shore

GRAPHIC: Ed Lustan/INQUIRER.net

The DENR also said the research could help guide future conservation planning across Leyte.

Regional Executive Director Arturo Salazar said the findings provide scientific information that can help determine which forest areas should be prioritized for protection.

“This study is both timely and highly relevant to ongoing conservation planning efforts in Leyte. As DENR and its partners consider which forest areas should be prioritized for protection and conservation, this research provides valuable scientific information that can help guide those decisions,” Salazar said.

He added that the study can also support future efforts to strengthen habitat protection.

“The study helps us understand which forest areas are most important for Philippine Eagle recovery and biodiversity conservation. This information can become an important basis for setting aside conservation zones, strengthening habitat protection measures, and supporting future protected area initiatives,” Salazar said.

The work continues

While the maps offer a science-based starting point, the researchers emphasized that they are not the final word on where future releases should take place.

“Ground validation of identified areas is strongly recommended to verify actual habitat conditions and address study limitations,” the researchers noted.

RELATED STORY: Philippine eagle faces higher risk of extinction, study finds

They also recommended using more detailed power-line maps and additional ecological data in future analyses to improve the identification of potential threats and suitable habitats.

For now, the study offers a roadmap for the next phase of the Philippine Eagle Reintroduction Program in Leyte.

For the researchers and conservation partners, the maps are only one part of a much larger effort. Turning them into a thriving wild population will require science, sustained forest protection and long-term cooperation among government, academe, conservation groups and local communities. /dm